1. Field of the Invention
The present invention relates to a semiconductor device and a method of fabricating the same and, more particularly, to a semiconductor device having highly reliable wires and a method of fabricating such a semiconductor device.
2. Description of the Related Art
With the increase in the degree of integration of a semiconductor device, the requirement for reliable wires is increasing. As wiring material of the semiconductor device, copper (Cu) has a higher melting point than aluminum (Al), and thus exhibits excellent electro-migration (EM) and stress-migration (SM) properties. As well, copper has low resistivity.
However, copper suffers because it diffuses in an insulating film formed of silicon or silicon oxide used in the semiconductor device, undesirably increasing current leakage or parasitic capacitance. With the goal of solving such a problem, a diffusion barrier is typically interposed between the copper layer and the insulating film.
In this way, the use of the diffusion barrier results in prevention of the diffusion of the copper layer. However, the diffusion barrier, having higher resistance than copper, is disadvantageously provided at the bottom of the via hole connecting the upper wire and the lower wire, leading to increased wire resistance.
In the case of forming a copper wire using a dual damascene process, due to heat stress applied to a dual damascene wire upon heat treatment process during subsequent semiconductor device fabrication processes, a huge stress-induced void (SIV) may be formed in the lower portion of the dual damascene wire. Such SIV results in poor electrical properties of the wire, deteriorating the reliability of the semiconductor device.